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Washington (CNN)Hackers, making good on a threat, published contact information for 20,000 FBI employees Monday afternoon, just one day after posting similar data on almost 10,000 Department of Homeland Security employees.

The hackers, tweeting from the account @DotGovs, claim they obtained the details by hacking into a Department of Justice database.

The hackers boasted on Twitter, "FBI and DHS info is dropped and that's all we came to do, so now its time to go, bye folks! #FreePalestine."

The information contained names, titles, phone numbers and email addresses. After the hackers published the data on the DHS employees on Sunday, they tweeted, "Well folks, it looks like @TheJusticeDept has finally realized their computer has been breached after 1 week."

The Justice Department is investigating the hack.

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Department spokesman Peter Carr told CNN it does not appear there was a breach of private personnel information, such as Social Security numbers.

"The department is looking into the unauthorized access of a system operated by one of its components containing employee contact information," said Carr. "This unauthorized access is still under investigation; however, there is no indication at this time that there is any breach of sensitive personally identifiable information. The department takes this very seriously and is continuing to deploy protection and defensive measures to safeguard information. Any activity that is determined to be criminal in nature will be referred to law enforcement for investigation."

The hackers taunted federal officials, tweeting, "When will the US government realize we won't stop until they cut relations with Israel."